ACTA AGRARIA DEBRECENIENSIS 2019-1
Promising Leuce poplar clones in sandy ridges between the rivers Danube and Tisza in
Hungary: a case study
1*Károly Rédei – 3Marianna Takács – 2Tamás Kiss – 2Zsolt Keserű
1University of Debrecen Faulty of Agricultural and Food Sciences and Environmental Management, Debrecen
2National Agricultural and Innovation Centre– Forest Research Institute, Deparment of Plantation Forestry, Püspökladány, Hungary
3University of Debrecen Faulty of Agricultural and Food Sciences and Environmental Management, Department of Animal Science,
An intensive integrated research and development work has been carried out on the improvement of Leuce poplars including primarily the
native white poplar (Populus alba L.) and its natural hybrid grey poplar (Populus × canescens). More than 70 percent of the Leuce poplar
stands can be found on calcareous sandy sites in the Danube–Tisza region, so they play a significant role in the poplar management of this
part of the country. The most important task ahead of Hungarian poplar growers is to improve the quality of poplar stands and plantations
based on selecting new clones and cultivars. The growth and yield of four promising Leuce poplar clones was evaluated on a marginal site in
central Hungary. The clones ‘H 425-4’ (Populus alba L. × Populus alba L.), and ‘H 758’ (Populus alba L. Mosonmagyaróvár 124) seem to
be suitable for wood production, while the ‘H 427-3’ (Populus alba L. × Populus alba L. cv. Bolleana) and ‘H 422-9’ (Populus alba L. ×
Populus grandidentata (Michx)) clones (with decorative stem form) could be better used for tree lines and ornamental plantations.
Keywords: Leuce poplars, clonal selection, experimental plantations
White poplar (Populus alba L.) and its most
important natural hybrid, the grey poplar (Populus ×
canescens (Aiton) Sm.) are native poplar species in
Hungary. The area of poplar stands and plantations in
the country was approximately 112 thousand ha in 2016
(5.5 per cent of the total forested land) (NÉBIH, 2016).
More than 70% of the white poplar stands can be
found on calcareous sandy sites on the Danube–Tisza
region. About 35% of the new afforestation and
artificial regenerations is carried out presently with
Leuce poplars in the mentioned region. They have a
rich gene pool on the sand dune region in the middle of
the Great Hungarian Plain and on the bottomland of big
rivers. In the future, due to the establishment of national
parks in these regions, considerable increases can also
be expected in the field of native poplars management.
At the same time their importance will be increasing in
the large areas of marginal sites which are not suitable
for hybrid poplars but can accommodate native ones.
In the Danube–Tisza region some very important
ecological factors have become unfavourable for poplar
growing in the last two decades. There is no sufficient
precipitation during the growing season (appr. 250-300
mm), and the rivers' control and canalisation have
caused a drastic lowering of the ground-water table in
many places. In such spots the water supply for poplars
depends on the moisture content of soils, accumulating
waters on the surface and on the water-storing capacity
of soils. Therefore, the main aim of the selection work
is to find and improve Leuce poplar clones and cultivars
that have good shape, provide good-quality wood
material for industrial purposes (without false
heartwood), and that can adapt to the global climate
changed conditions (Rédei, 1991, 1999, 2000).
BRIEF SUMMARY ON BREEDING AND
IMPROVEMENT OF POPLARS IN HUNGARY
The basis for the breeding and improvement
programme was a series of clones given in the frame of
co-operation, during the 1950’s by the Poplar Research
Institute of Italy, Belgium, the Netherlands, France,
Germany and Yugoslavia, combined with the genetic
heritance of Hungarian forests (Populus nigra L. and
Populus alba L.). This research programme was started
by the prominent scientists of the Hungarian Forest
Research Institute (FRI), Gy. Koltay and F. Kopecky. In
Hungary FRI (at present NARIC-FRI) is the most
important national institution for poplar breeding and
improvement. It took part in provenance testing
experiments of Populus trichocarpa (Torr. & A. Gray
ex. Hook), Populus deltoides (W. Bartram ex Marshall)
and Populus nigra L., which were launched by FAO
and IUFRO. Due to breeding activities over four
decades, about 80 000 seedlings were produced and
tested by FRI, of which 50% were among interspecific
and intraspecific hybrids of the Aigeiros section, 15%
of the Leuce section and 35% of the Tacamahaca
section (Kopecky, 1962, Tóth,1996).
The number of clones selected out of progenies
amounts to more than 1000. These clones, screened by
early testing methods, make up a considerable part of
the collection of FRI and at the same time primary
materials for clonal testing experiments. This poplar
cross-breeding resulted in several excellently growing
euramerican poplar clones, of which Populus ×
euramericana (Moench) 'Pannonia', 'Kopecky' and
'Koltay' have been admitted to the official national
poplar clone-choice and are integral parts of the state
approved and tested varieties.
ACTA AGRARIA DEBRECENIENSIS 2019-1
Selection breeding was mostly directed to native
poplars (Kopecky, 1962, 1978). According to his
research on native poplar hybrids, the P. alba L. x P.
grandidentata (Michx) ‘H 422-1’, the ‘H 422-6’, the P.
alba L. x P. alba L. ‘H 425-4’ and the ‘H 325-10’ clones
could have some growing-importance. The P. alba L.
cv. ‘Bolleana’ ‘H 427-3’, the P. alba L. × P.
grandidentata (Michx) ‘H 422-1’ and the ‘H 422-6’
clones can be planted in roadside plantations and parks
for their decorative value on the whole range of suitable
sites. On the calcareous sites of the Great Plain only the
P. alba L. cv. ‘Bolleana’, the ‘H 372-1’ and the ‘H 372-
2’ can be planted.
Selection investigations on marked individuals and
populations of native poplars laid the foundation for
their possible in situ and ex situ conservation (Keserű
et al., 2005). Marked gene-reserves extend to roughly
100 ha and the number of registered plus-trees is about
200 (in situ gene preservation). In Hungary the area of
native and hybrid poplar experiments amounts to 400
ha. Geographically they are dispersed in the poplar
growing regions, and therefore are suitable for drawing
conclusions on clone-site relations under the typical
conditions of the country.
Suitable observation techniques make it possible to
observe some characteristics important for breeding
already at an early stage of development of trees, while
other characteristics are manifested at a later age. The
responses of clones under different environmental
conditions is a result of their greater or smaller
adaptability in regard to survival, rate of growth,
resistance to damages, etc.
Description of study area
In the past 20 years the Hungarian Forest Research
Institute established several comparative trials with
Leuce poplar clones for investigating their site
requirements, growing patterns and yield. The trial
discussed in this paper was allocated in subcomparment
Szentkirály 40G in the Danube–Tisza interflow region
(Figure 1) in spring 1988, with the following clones:
‘H 427-3’ (Populus alba L. × Populus alba L. cv.
‘H 758’ (Populus alba L. Mosonmagyaróvár 124),
‘H 425-4’ (Populus alba L. × Populus alba L.),
‘H 422-9’ (Populus alba L. × Populus
control (common white poplar).
Figure 1: Location of the study site
The experiment was set up with one year old
seedling in a randomised block system with three
replications. The initial spacing was 2.0 x 2.0 m. The
control white poplar and the third replication of the
clones, due to the unfavourable site conditions, died out
at the age of 2. Because of this the characteristics of the
main part of a white poplar stand of Yield Class I (Yield
table: Rédei, 1991) was considered as control with the
following values: mean height = 21.4 m; mean DBH =
24.5 cm; mean tree volume (according to the volume
table for white poplar) = 0.501 m3/tree at the age of 20.
According to the Hungarian classification of forest
site types, the main ecological characteristics of the
study area are the following: forest steppe climate zone:
humidity is less than 50% in July at 2pm, the annual
precipitation is less than 500 mm, hydrology: free
draining genetic soil type: humid sand soil with very
shallow rootable depth (<20 cm) with 0.1 % of total salt
Assessment of tree and stand characteristics
The following stand parameters were measured and
calculated at the age of 5, 10, 15 and 20 years: stem
number, dbh (diameter at breast height), basal area, tree
height, stem volume, stand volume and mean tree
volume. Stem volume was estimated by the following
volume function (Sopp, 1974):
where d is diameter at breast height (d1.3, cm), h is tree height (m), po= 2, p1= - 4236, p2=12.43, p3=4.6, p4=3298.
Then we can calculate the total volume per ha (V):
V = vN, where N = stem number per ha.
Tree quality classification
To characterize tree quality, the stem quality index
at the age of 20 was defined, by using the following
stem quality classes: Class 1 - The stem is straight,
cylindrical, healthy and reaching the top of the crown.
Class 2 - The stem is straight and healthy, forks are
tolerated, but only if they are in the uppermost third of
the tree. Class 3 - The stem is crooked, leaning and
ACTA AGRARIA DEBRECENIENSIS 2019-1
more or less damaged. Class 4 - The stem is very
crooked in more than one dimension and heavy
damaged. The stem quality index was calculated as the
average of the stem classes weighted by stem number.
The statistical analyses were carried out ANOVA
Program (STATISTICA 8.0 data analysis software
system - StatSoft, Inc. 2008).
Some yield data and the relevant percentage-values
compared to the control calculated on the basis of
replications’ means at the age of 20 can be found in
On the basis of the data, considering the growth in
height, and dbh the clone ‘H 425-4’ provided the best
result. It overpassed the control by 6 and 4 per cent,
respectively. The tendency is the same with regard to
the mean tree volume values. The effect of differences
in dbh. on the mean tree values seems to be
considerable (additional 8 per cent for the above-
mentioned clone). As the tree quality index is
concerned, the succession from best to worst is: ‘H 425-
4’, ‘H 758’ ‘H 427-3’ and ‘H 422-9’.
According to the significance test at P=5% level,
significant differences were found in dbh (SD5%=7cm)
and in the mean tree volume values (SD5%=0.144 m3).
The trees in the clone trial, as it was mentioned
above, thrive under marginal site conditions that are
normally unfavourable for poplar growing.
Considering this fact, the early evaluation showed that
all the examined Leuce poplar clones are promising for
growing on the above-described sites. The clones ‘H
425-4’ and ‘H 758’ seem to be suitable for wood
production, while the ‘H 427-3’ and ‘H 422-9’ ones
(with decorative stem form) could be better used for
tree lines and ornamental plantations. The clone
marked ‘H 425-4’ has been registered as cultivar-
Yield data of white poplar clones at the age of 20 (replications’ means)
Mean tree volume
* data derived from yield table (Rédei, 1991)
The selected Leuce poplar clones have to fulfil the
following criteria (Mátyás, 1983): intensive early
growth to outcome cultivation stage as far as possible;
straight stem to keep mechanical processing; fine
branching; good rooted ability; variable felling age, to
enable us to prolongation the rotation age; coarse bark
(increases tolerance against game damage), and
differences among clones in the phenology of bud burst
which helps to prolong the planting period. As the
results suggest, systematic testing is essential in poplar
breeding. However, results with smaller probability of
error can only be achieved after a long period of
research. The systematic evaluations of clone trials set
up in the past decades in Hungary will make it possible
to select Leuce poplar clones more reliably which can
meet all the requirements drafted in the introduction to
Keserű, Zs.–Balla, I.–Antal, B.– Rédei, K. (2015)
Microporopagation of Leuce poplars and evaluation of their
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